Epidemiology

The overall incidence has increased over the last few decades and is currently thought to affect 1-2% of pregnancies. The risk is as high as 18% for first trimester pregnancies with bleeding 14. There is an increased incidence associated with in-vitro fertilisation pregnancies.

Clinical presentation

The classic presentation is with abdominal pain and bleeding. In practice, the symptoms are not necessarily severe - often there may be only mild pelvic pain and spotting in early pregnancy (5-9 weeks of amenorrhea 5). Nonetheless, monitoring of hemodynamic status is crucial, as hemorrhage can be life threatening.

Pathology

Locations

In the vast majority of cases, the ectopic implantation site is within a Fallopian tube.

maternal age (advanced maternal age increases the risk of ectopic pregnancy)18

history of subfertility 19

Markers

Serum beta HCG levels tend to increase at a slower rate. Whereas a normal doubling rate in early pregnancy is approximately 48 hours, an increase of 50% or less in 48 hours is strongly suggestive of a non-viable (either intra- or extrauterine) pregnancy 10. Rarely the urinary and/or serum b-HCG will be negative despite an ectopic pregnancy 12.

Serum progesterone levels are generally lower in a non-viable (including ectopic) pregnancy 6; progesterone of 5 ng/ml or less is strongly associated with pregnancy failure, whereas in a viable pregnancy, progesterone is usually 20 ng/ml or more 5. Clearly, there is a significant grey zone. Furthermore, serum progesterone levels may take days to process. Progesterone is therefore not included in standard protocols for managing the suspected ectopic pregnancy.

Radiographic features

It is useful to know a quantitative beta HCG prior to scanning as this will guide what you expect to see. At levels <2000 IU, a normal early pregnancy may not be visible.

The most reliable sign of ectopic pregnancy is the visualization of an extra-uterine gestation, but this is not seen in 15-35% of ectopic pregnancies 3.

Ultrasound

The ultrasound exam should be performed both transabdominally and transvaginally. The transabdominal component provides a wider overview of the abdomen, whereas a transvaginal scan is important for diagnostic sensitivity.

free fluid in Morison's pouch in the context of an ectopic pregnancy is highly suggestive that operative management will be necessary 20

live pregnancy: 100% specific, but only seen in a minority of cases

In patients receiving in vitro fertilisation (IVF), it is important not to be completely reassured by the presence of a live intrauterine pregnancy 8, as there is a possibility of a coexisting ectopic pregnancy in ~1-3:100 17 (i.e. heterotopic pregnancy). In patients not receiving IVF, the risk of heterotopic pregnancy is minuscule (1:30,000).

Complications

Complications somewhat depend on the type of ectopic. General complications for a typical (tubal) ectopic pregnancy include:

The scenario of clinically suspected ectopic pregnancy that is not confirmed on ultrasound, is referred to as a pregnancy of unknown location, with the alternative possibilities being of very early pregnancy or a completed miscarriage.

Quiz questions

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